In the sport of windsurfing, a rider stands on a sailboard that is floating on a body of water. A mast member is movably mounted on the sailboard and a sail is mounted to the mast member. Typically, the mast member is mounted to the board via a rubber gooseneck fitting. As wind hits the sail, the sailboard is propelled across the water. By altering the position of the mast member and sail with respect to the sailboard, the rider can change speed and direction of the sailboard.
The axial loads exerted onto the sailboard by the mast member can be significant in competitive and/or high-performance windsurfing applications such as racing and/or performing tricks. These loads are further increased by high winds and choppy water. For example, when a sailboard jumps from the crest of a wave into the trough of the wave, significant loads are exerted from the mast member onto the sailboard. It is known that these perpendicular loads between the mast member and the sailboard can permanently damage the sailboard. This problem is exacerbated by the desire to have lighter weight sailboards (which are typically more fragile) for competitive racing and for performing tricks.
Recently, mechanical universal joints have been used instead of gooseneck fittings to improve the transfer of motive force from the sail to the board. However, this direct mechanical link between the mast member and the board also serves to more directly transfer axial loads, and thus further increases the chances of damage to the board.
Conventional methods to prevent the sailboards from becoming damaged by the stress exerted by the mast member include making the surface of the sailboards harder and stronger using material such as fiberglass cloth or cloth impregnated with carbon. However, these materials increase the cost of the sailboards, can increase the weight of the sailboard, and do not decrease the load the mast member exerts on the sailboard.
Use of an oil-filled cylinder or a gas spring, similar to an automotive-type shock absorber, between the mast member and the sailboard is also known. However, these approaches add significant weight to the sailboard system which is a measurable disadvantage in the high-performance sailboard market.
To attach a mast member to a sailboard, a unshaped spring pin made of metal is conventionally used. These pins derive their spring force from the bent u-shape of the pin. However, as the metal fatigues, the spring force of the pin decreases.